Production of silicic acid



I Nov. 24, 1925- 1 N. L. COLLINS PRODUCTION OF SILICIC ACID Filed March27, 1924 I hale/7&1 .JweZZ.

Past Nev. 24, 1925.

' NEWELL L. COLLINS, OF'CLABINDA, IOWA.

rnonvcrion or sILIcIc sen).

Application filed March 27, 1924. Serial No. 702,364.

To all whom z'tmay concern: Y

' Be it known that I, NEwnLL L. COLLINS, a 1 citizen of the United'States, residing at Clari'nda, in the county of Page and Stateof Iowa,have invented certain new and useful This invention relates to theproduction of Improvements iu'the Production of Silicie Acid, of whichthe following is a specification, reference being had to theaccompanying drawings.

silicic acid and has 'for animportant object thereof theproduction .ofpure silicic acid 1 by a relatively cheaper and rapid process. -Afurther object of my invention is to pro- 5 vide pure silicic acid to beas a hydrosol or hydrogel as desired. As a hydrosol it may beset to agel in the-presence of well-known substances.

Heretofore it has only been possible to .produce'pure silicic acid as ahydrosolv by a long'andimpractical process in which the impurities aredialiaed from the silicic acld. Silica gel has been produced on a, largescale and this when dialized results in purified 1 3" silicic acid. Thislast method, however, is

disadvantageousv in that the hydro'sol form ,cannotbesecured and afurtherdisadvantags in that the silicicacid tlms-secured-containsimpurities notably sodium. Impurities present in silicicacid, as in thepresent manufacture, render the same unfit for the particular use forwhich it is the purpose of this invention to provide silicic acid,namely, for use in a seml-dry storage battery, the pres- ,ence'of sodiumhaving to date rendered the .use of silieic acid in such batteries withany degree of efliciency impossible.

Inaccorda nce wlth my process I'employ 'a l good grade ofwater glasshaving aspecific 'ravity of about 1.37 which I dilute with tree parts ofdistilled water. This solution is then subjected to electrolysis between'a'rapidly rotatingnon-corrosive anode and a mercury cathode. The use oflead in the construction of the anode has been found. advantageous.Current of about four or. five amperes per square decimeter of anodesur- .face 'has been found most efiicientalthou h I I amountean bevaried without materia dy altering the results obtamed. .A good gra, e

of water 'glass consists of a solution 'of so- I l di'um silicate andsodium hydroxide. The

' will; be"deposited*in the mercury cathode with a current efliciencyandit ,has

5 Ibeen'iound that by employing this process the sodium-will be deposted in the mercury with a current efliciency of nearly 100%.

Oxygen from the water is deposited at thei I rotating anode and thehydrogen of the water takes the place of the sodium'of the water glassforming silicic acid. The reaction may be represented approximately asfollows ess. This apparatus consists of an outer container 10 withinwhich is disposed an open In the accompanying drawings I havebottomcylinder 11 of less external diameter than the internal diameter of thecasing 10, the bottom of the cylinder being in slightly spaced relationto the bottom ofthe outer casing 10 to thereby provide a passageway 12.In the bottom of the container 10 the mercury cathode 13 is disposed,the mercury being of a depth at least covering the upper end of thepassageway 12 and sealing communication between the main compartment 14,represented by the space within the cylinder 11 and above the bottom ofthe casing 10, and the auxiliary compartment 15, represented by thespace between the outer wall of the sleeve and the inner wall of thecasing. The mercury, of course, extends into the compartment 15 tothe-same level as it is in the compartment 14. Suspended in thecompartment 14 isa lead anode supported above the casing 10, as at 17,for rotation and driven as by a belt 18 from a suitable source cury ispassed through the space 12 into the outer compartment 15.- In thisouter com .partm'ent the sodium-is constantly removed from the mercuryeither byplacing in the compartment-15 above the mercury a sul-- phuricacid solution or by employing a sodium hydroxide solution. in which acathode 19 is immersed. IVhen the sulphuric acid f-solution is employed.sodiumsulphate is formed and when the sodium hydroxide solutionwitlr thecathode 19. is employedof power. The Water glass solution is placedsodium hydroxide is formed. Either of these by-products would bevaluable and at the same time the system of removing from the mercurythe sodium combining therei with permits the use of a relatively-smallamount of mercury and its use simply as a transportation element for thesodium from the water glass solution to the point of withdrawal.

Figuring the amount of sodium "in the water glass as 8% and knowingthecurrent, it is possible to calculate the end of the run very closelyfrom the following formula:

Time equivalents of sodium X 96500 3600 X ampere's I It has been foundthat by the use of the process above set forth it is possible to secure,to all practical purposes, a 100% I moval of sodium from the Waterglass. The

' removed If it is desired to retard the setsi icic acid solution setsto a gel a few hours a ter the last traces of the sodium have been tingof the gel fora considerable length of time, the process can beinterrupted before the sodium is completely removed. A very smallpercentage of sodium does not harm the silicic acid for most purposes,it merely acts as a peptization agent retarding the setting of thesilicic acid to a gel for several days. It has further been found thatby the use of an apparatus employing the rotating anode, as above uponthe anode can be prevented, particularly when, the waterglass isproperly di luted. It is pointed out that ifthis silic de osit u on theanode'is not prevented'not on y won the silica would iii-time serve asaninsulation for the anode preventing'passag'e of cura,

rent through the-solution. Silicic acid pro-v for rotating onedescribed, the silica deposit d, the aqueous solution become so dilutedin strength as to become useless, but

duced by this process has been-found-tobe entirely satisfactory forusein the semi-dry storage battery construction above referred to anditwill be obvious that the process employed may be very cheaply andreadily car ried out. Particular attention is directed to the fact thatby this process substantially gel form can be obtained.

I claim 1. A process of producing pure silicic acid consisting inelectrolyzing an aqueous solut1on of waterglass between an .anode andaacid' comprising an electrolyte jar having two compartments,'an anodedisposed in eac pure sllicic acid in either hydro'sol orhydrocompartment, a mercury cathode common to I both compartments andsealing communication between the compartments, of said anodes. 5,Apparatus for producing pure silicic acid by electrolysis comprising anelectrolyte jar'having two compartments, a mercury cathode sealingcommunicationbetween the I compartments,

ment, and means an an de within one compartfor rotating the anode..

and means In testimony-when of hereunto afiixuny signature-.;

QNEW'ELL L- CQL S

